Heater cut-out for electric lamps.



' Patented Oct. 29. I90l. H. N. POTTER.

HEATER CUT-OUT FOR ELECTRIC LAMPS.

.(Application filed Aug. 15, 1900. Renewed Sep(:. 6, 1901.)

(No Model.)

Fig. 1.

WITNESSES INVENTOR B l A'TTdm/Er.

m: norms PETERS o0. PHOTO-Undo" WASHINGYONA 0.6.

UN lTE- STATES PATENT OFFICE.

HENRY NOEL POTTER, OF HALENSEE, GERMANY, ASSIGNOR TO GEORGEXVESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA;

SPECIFICATION forming as be Letters Patent No, 68 5,488, dated October29, 1901.

Application filed August 15,1900. Renewed September 6, 1901. Serial No.74,577. (No model.)

To all whom it may concern/.-

Be it known that I, HENRY NOEL POTTER, a citizen of the United States,residing at Halensee, in the Kingdom of Prussia and Empire of Germany,have invented a new and useful Improvement in Heater Cut-On ts forElectric Lamps, of which the following is a specifical'lOlL I Myinvention relates to electric lamps of the type in which theilluminating body or glower is a conductor only when hot; and it hasparticular reference to the means for eutting out of circuit the heatersemployed for raising the temperature of the glowers in such lamps to theconducting-point.

The object of my invention is to provide an electromagnetic heatercut-out which will be operative under the action of a comparativelysmall percentage of the glower-current without unduly increasing eitherthe size of the cut-out coil or the expense of its manufacture and atthe same time avoiding the injuries caused by excessive heat due to theconsumption in the coil of an excessive quantity of energy. With theseends in view I have devised the means shown in the accompanying circuitsupplying a plurality of lamps in seballasts, particularly the latter,since they are not capable of withstanding an excessivecurrent-overload. In order to overcome the difficulties incident to suchcondition and operation, I propose to employ a sensitive heater cut-outwhich will serve to interrupt the heater-circuit before the glower takessufficient current to render the combinedheate'r and glower current ofthe particularlamp thus operating dangerous to the lamps of the seriesalready in operation. 1

Referring now particularlyto the drawings, the circuit 1 is suppliedwith energy either directly or through a transformer from a main circuit2, fed by a constant-potential generator 2. Thelamps 3, of which ten areshown in Fig. 1, will obviously be designed individs ually for suchvoltage that the number con nected in series will be adapted to thevoltage supplied to the circuit either directly or indirectly from thecircuit 2. The glower 4 of each lamp is supplied with current through aballast device 5 and is heated to conducting temperature bya suitableheater 6, as is usual in this class of lamps. The cut-out for theheater-circuit comprises a magnet-winding 7, a core 8 therefor, and amovable contact member 9, that normally rests in contact with astationary contact-terminal 10 and is moved into contact with a secondstationary contact-terminal 11 when the magnetis energized. Thecontact-terminal 10 is connected to one terminal of the heater 6 and thecontact-terminal 11 to a suitable point intermediate the ends of theWinding 7. The two parts 12 and 13 of the winding 7, between which theterminal 11 is connected, may be considered as separate coils connectedtogether or as parts of a single winding. One terminal of the winding 7is connected through the ballast device 5 to one terminal of the glower.

cut-out. It will be readily seen that when the glower is raised toconducting temperature by means of the current traversing the heatercurrent will flow through the entire coils '7, and by reason of thelength and consequent resistance of such coil the amount of current willnot be sufficient to endanger the otherlamps in this series,but thesmall amount of current is sufficient to lift the member 9 intoengagement with the stationary contactterminal 11, and when brought tothat position the part 12 of the winding 7 will be shortcircuited.

It has been found in practice to be feasible The other terminal of thewinding is connected to the movable member 9 of the to employ a magneticcut-out of the usual type which will interrupt the heater-circuit uponthe passage of one-half the full glowercurrent and which will not becomeunduly heated nor be extremely wasteful of energy when traversed by theentire current of the glower; but an attempt to employ a cut-out whichwill interrupt the heater-circuit when traversed by a small percentage,even as high as twenty-five per cent. of the normal glowercurrentinvolves difficulties on account of the size of the coil necessarilyemployed and the consequent expense of manufacture and the heating inuse. With my present arrangement the heater-circuit is interruptedbefore the glower takes sufficient current to render the combined heaterand glower current dangerous to other lamps in the series, and theshort-circuiting of the part of the magnetwinding leaves only sufficientwinding in circuit to maintain the heater-circuit in open condition.

My invention is not necessarily limited to use in connection with lampsoperated in series in a constant-potential circuit, and I thereforedesire it to be understood that variations in this respect, as well asin others, may be made without departing from the invention.

I claim as my invention- 1. In an electric lamp of the type described,the combination with a glower and a heater therefor, of a heater cut-outhaving two coils primarily connected in series with the glower andhaving means for cutting out one of said coils after the heater is cutout.

2. In an electric lamp of the type described, the combination with'aglower and a heater therefor, of a heater cut-out comprising two coilsconnected to form a single winding for breaking the heater-circuit andmeans for short-circuiting one of said coils after the heater-circuit isbroken.

3. In a constant-potential electric circuit, a plurality of electriclamps of the type described connected inseries each of which has aheater cut-out comprising a magnet and means for short-circuiting a partof said winding immediately after the heater-circuit is interrupted.

4. In a constant-potential electric circuit, a plurality of lampsconnected in series each of which has a glower and heater and a heatercut-out comprising an actuating-magnet, a movable member and twocooperating contact-terminals connected respectively to oneheater-terminaland to an intermediate point in the magnet-winding,whereby the entire magnet-windingis utilized to break the heatercircuitand a portion of the same is immediately thereafter short-circuited.

In testimony whereof I have hereunto subscribed my name this 31st day ofJuly, 1900.

HENRY NOEL POTTER.

Witnesses:

HENRY HASPER, WILLIAM MAYNER.

